We will continue our investigaton on three areas originally described in our grant applicaion most of which have been followed over the past ten years: I. The relationship between calcium ATPase and calcium transport and the control of these will be pursued. In addition to kinetic studies, examination of the effects of altering lipids and the lipid environment of the purified calcium ATPase from cardiac and skeletal muscle will be examined. Finally, hydrogen ion concentration has been found to be a very sensitive probe to examine the relationships between calcium transport and calcium ATPase and many factors which result in pH sensitivity of calcium transport have been particularly revealing. This will be examined under circumstances of varying substrate concentrations. II. Sarcoplamic Reticulum-Glycogenolytic Complex - Current investigation involves comparison of beta-adrenergic receptors in this complex as compared to sarcolemmal beta-adrenergic receptor to try to clarify whether or not a distinct beta-adrenergic receptor is found in sarcoplasmic reticulum fragments. Purification of sarcoplasmic reticulum preparations has proceeded to the point where no measurable sodium-potassium ATPase or ouabain binding can be discerned. In addition, investgation of the mechanism of coupling of both the activating phosphatase enzymes to phosphorylase in skeletal muscle SR glycogenolytic complexes is being pursued. III. Microtubules -Further investigation in both morphologic and biochemical and cardiac microtubules is proceeding. Currently we are optimizing conditons for the formation of microtubules in vitro and examining other morphologically distinct forms also produced under varing conditions by the same general protein mixture.